The present invention relates to an electronic musical instrument having a plurality of musical sound synthesizing circuits which have different tone generation mechanisms.
Conventionally, the electronic musical instrument has musical sound synthesizing means which produces a musical sound in a timbre specified by timbre designation information. The timbre designation information is externally supplied to the electronic musical instrument to create a timbre for a produced musical sound.
One type of the electronic musical instrument has a wide variety of available timbres. Another type of the electronic musical instrument has only a small number of available timbres. When an electronic musical instrument having only a small number of timbres is supplied with timbre designation information which specifies a timbre not available by the instrument, it cannot produce a sound by the specified timbre. However, it is unnatural for the electronic musical instrument not to produce a sound while receiving a tone generation command to request sound production. Thus, as disclosed in Japanese Patent Application Laid-open Publication No. 4-7519, the specified timbre is replaced by a substitute timbre which can be created by itself, whereby a sound is successfully produced.
Regarding tone generation mechanisms adopted in the musical sound synthesizing means of the electronic musical instrument, in addition to a conventional FM synthesis mode and a waveform reading mode, a physical model mode is recently developed, which is designed to simulate physical behavior of a natural musical instrument to synthesize a musical sound. As for the electronic musical instrument of the physical model system, a wind instrument type is disclosed in Japanese Patent Application Laid-open No. 3-65999, and a piano type is disclosed in Japanese Patent Application Laid-open No. 3-58096. The physical model system is superior to the conventional sound producing systems in an extent of variations of timbres, and is capable of synthesizing high-quality musical sounds.
In MIDI (Musical Instruments Digital Interface) standard which prescribes transaction scheme of signals between electronic musical instruments, a timbre coding system is recently introduced, which aims at reproducing substantially the same quality of a musical tone in diverse models of any maker by standardizing timbre designation information. The common coding system is based on a timbre table registered in a waveform memory type of the sound source which can prepare many waveforms relatively easily to cover a practically sufficient variety of timbre species.
However, when a musical sound of a natural musical instrument is to be simulated, it is necessary for the sound source of the aforesaid physical model system to use a specific program designed according to a mode of generating a musical sound associated to strings to be twanged, strings to be rubbed, reeds and the like, in contrast to the waveform memory type of the sound source which employs sampling of natural sounds. Thus, the sound source of the physical model system is not good for preparing a wide variety of timbres. Accordingly, a sound source of the waveform memory type and another sound source of the physical model type are integrated into a single electronic musical instrument. Sound production by the physical model type sound source is effected for limited timbres, and sound production by the waveform memory type sound source is effected for the rest, whereby high-quality musical sounds can be synthesized while maintaining coverage of the wide variety of the timbres.
When high-quality musical sounds are synthesized by the composite electronic musical instrument, timbres may be safely changed within the limited variety of the timbres in accordance with internal setting by a player. However, in case of producing a musical sound based on externally provided timbre code data which is prepared in accordance with the aforesaid timbre table, a timbre of the sound source of the waveform memory type is automatically selected in spite of the high-quality sound source of the physical model type being provided. Namely, the musical sound is synthesized and produced by the selected waveform memory type sound source with low-quality. A conceivable method for avoiding this is to share the timbre table by both of the waveform memory type sound source and the high-quality physical model type sound source. However, a ready-made waveform memory is difficult to rewrite waveforms. It is wasteful to abandon the ready-made waveform memory. Furthermore, a complex table configuration must be formed if the same is shared commonly by the different types of the sound sources. Also, as described later, in simulating the same musical instrument, the conventional waveform memory type sound source may have a better performance for certain usage than the physical model type sound source. Thus, it is preferable that a timbre table should be prepared for each of the musical sound synthesizing systems.